jpeg_rgb_decoder.c

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#include <glib.h>
#include <stdio.h>
#include <string.h>

#include "jpeg_rgb_internal.h"
#include "jpeg.h"


static void convert(JpegRGBDecoder *rgbdec);

static void imagescale2h_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int src_rowstride, int width, int height);
static void imagescale2v_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int src_rowstride, int width, int height);
static void imagescale2h2v_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int src_rowstride, int width, int height);
static void scanlinescale2_u8(unsigned char *dest, unsigned char *src, int len);


JpegRGBDecoder *jpeg_rgb_decoder_new(void)
{
	JpegRGBDecoder *rgbdec;

	rgbdec = g_new0(JpegRGBDecoder, 1);

	rgbdec->dec = jpeg_decoder_new();

	return rgbdec;
}

void jpeg_rgb_decoder_free(JpegRGBDecoder *rgbdec)
{
	int i;

	jpeg_decoder_free(rgbdec->dec);

	for(i=0;i<3;i++){
		if(rgbdec->component[i].alloc){
			g_free(rgbdec->component[i].image);
		}
	}

	g_free(rgbdec);
}

int jpeg_rgb_decoder_addbits(JpegRGBDecoder *dec, unsigned char *data,
	unsigned int len)
{
	return jpeg_decoder_addbits(dec->dec, data, len);
}

int jpeg_rgb_decoder_parse(JpegRGBDecoder *dec)
{
	return jpeg_decoder_parse(dec->dec);
}

int jpeg_rgb_decoder_get_image(JpegRGBDecoder *rgbdec,
	unsigned char **image, int *rowstride, int *width, int *height)
{
	int i;

	jpeg_decoder_get_image_size(rgbdec->dec, &rgbdec->width,
		&rgbdec->height);
	for(i=0;i<3;i++){
		jpeg_decoder_get_component_ptr(rgbdec->dec, i+1,
			&rgbdec->component[i].image,
			&rgbdec->component[i].rowstride);
		jpeg_decoder_get_component_subsampling(rgbdec->dec, i+1,
			&rgbdec->component[i].h_subsample,
			&rgbdec->component[i].v_subsample);
		rgbdec->component[i].alloc = 0;
		if(rgbdec->component[i].h_subsample>1 ||
		   rgbdec->component[i].v_subsample>1){
			unsigned char *dest;
			
			dest = g_malloc(rgbdec->width * rgbdec->height);
			if(rgbdec->component[i].v_subsample>1){
				if(rgbdec->component[i].h_subsample>1){
					imagescale2h2v_u8(dest,
						rgbdec->width,
						rgbdec->component[i].image,
						rgbdec->component[i].rowstride,
						rgbdec->width,
						rgbdec->height);
				}else{
					imagescale2v_u8(dest,
						rgbdec->width,
						rgbdec->component[i].image,
						rgbdec->component[i].rowstride,
						rgbdec->width,
						rgbdec->height);
				}
			}else{
				imagescale2h_u8(dest,
					rgbdec->width,
					rgbdec->component[i].image,
					rgbdec->component[i].rowstride,
					rgbdec->width,
					rgbdec->height);
			}
			rgbdec->component[i].alloc = 1;
			rgbdec->component[i].image = dest;
			rgbdec->component[i].rowstride = rgbdec->width;
			rgbdec->component[i].h_subsample = 1;
			rgbdec->component[i].v_subsample = 1;
		}
	}

	rgbdec->image = g_malloc(rgbdec->width * rgbdec->height * 4);

	convert(rgbdec);

	if(image) *image = rgbdec->image;
	if(rowstride) *rowstride = rgbdec->width * 4;
	if(width) *width = rgbdec->width;
	if(height) *height = rgbdec->height;

	return 0;
}


/* from the JFIF spec */
#define YUV_TO_R(y,u,v) CLAMP((y) + 1.402*((v)-128),0,255)
#define YUV_TO_G(y,u,v) CLAMP((y) - 0.34414*((u)-128) - 0.71414*((v)-128),0,255)
#define YUV_TO_B(y,u,v) CLAMP((y) + 1.772*((u)-128),0,255)

static void convert(JpegRGBDecoder *rgbdec)
{
	int x,y;
	unsigned char *yp;
	unsigned char *up;
	unsigned char *vp;
	unsigned char *rgbp;

	rgbp = rgbdec->image;
	yp = rgbdec->component[0].image;
	up = rgbdec->component[1].image;
	vp = rgbdec->component[2].image;
	for(y=0;y<rgbdec->height;y++){
		for(x=0;x<rgbdec->width;x++){
			rgbp[0] = YUV_TO_R(yp[x], up[x], vp[x]);
			rgbp[1] = YUV_TO_G(yp[x], up[x], vp[x]);
			rgbp[2] = YUV_TO_B(yp[x], up[x], vp[x]);
			rgbp[3] = 0;
			rgbp+=4;
		}
		yp += rgbdec->component[0].rowstride;
		up += rgbdec->component[1].rowstride;
		vp += rgbdec->component[2].rowstride;
	}
}


static void imagescale2h_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int s_rowstride, int width, int height)
{
	int i;

	for(i=0;i<height;i++){
		scanlinescale2_u8(dest + i*d_rowstride, src + i*s_rowstride,
			width);
	}

}

static void imagescale2v_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int s_rowstride, int width, int height)
{
	int i;

	for(i=0;i<height;i++){
		memcpy(dest + i*d_rowstride, src + (i/2)*s_rowstride,
			width);
	}

}

static void imagescale2h2v_u8(unsigned char *dest, int d_rowstride,
	unsigned char *src, int s_rowstride, int width, int height)
{
	int i;

	for(i=0;i<height;i++){
		scanlinescale2_u8(dest + i*d_rowstride,
			src + (i/2)*s_rowstride, width);
	}

}

static void scanlinescale2_u8(unsigned char *dest, unsigned char *src, int len)
{
	int i;

	for(i=0;i<len;i++){
		dest[i] = src[i/2];
	}
}